1. Field of the Invention
This invention relates to a medical devices which have a segment which is inserted into the body and a segment which is retained outside the body for manipulation. In particular it relates to such structures in which the a portion of the in-the-body segment is coated with a lubricious coating material.
2. Description of the Related Art
Medical devices, such as catheters and guide wires, designed to navigate the passageways, channels, canals, cavities, and other interior parts of a patient, serve a variety of purposes including the delivery of biologically compatible fluids to a site within the body, such as radiologically opaque fluid for contrast x-rays, the delivery of a stent to a desired location within the body, the delivery of a balloon to a desired location to widen a vessel and the delivery of a fiber optic cable to a desired location.
These applications require smooth devices exhibiting a certain degree of lubricity so as to avoid injuring the mucous membranes and other bodily parts with which they come in contact. Depending on the intended use of such a device, the requirements for lubricity along the surface of the device may vary widely. In the case of balloon catheters, it is desirable for the balloon to have a lubricating portion and a non-lubricating portion to avoid the so-called `watermelon seed` problem wherein a balloon which is too lubricious shoots forward on inflation. To this end, U.S. Pat. No. 5,503,631 Onishi et al. discloses a vasodilating catheter balloon whose body has a lubricating portion and a non-lubricating portion. The lubricious property of the balloon is created by grafting a lubricious coating onto a non-lubricious substrate.
U.S. Pat. No. 3,826,674 to Schwarz discloses a lubricious coating based on a hydrophilic polyurethane foam where the lubricity is imparted through the use of an anhydride coating. Schwarz further discloses that the anhydride can be made more hydrophilic via treatment with a low molecular weight amine.
U.S. Pat. No. 4,876,126 to Takemura et al discloses a medical instrument that exhibits low frictional resistance when wetted with aqueous solutions e.g. body fluids. The instrument is prepared by treating a substrate with a solution containing a reactive functional group to form an undercoat and then treating the substrate with a water soluble polymer such as a maleic anhydride polymer to covalently bond the reactive functional group with the water soluble polymer. The water soluble polymers disclosed are chain structured, non-cross-linked polymers having a hydrophilic group.
U.S. Pat. No. 5,229,211 discloses a medical device with a reduced lubricity on the out-of-body end to aid in manipulating the device from outside the body. This reduced lubricity is achieved by treating the basal part with an isocyanate prepolymer to reduce hydrophilicity relative to the proximal part of the device.
U.S. Pat. No. 5,441,488 to Shimura et al discloses a medical device having a lubricious surface in a wetted state. The device comprises a substrate and water-swellable polymer coating. The coating is bonded via a reaction between a functional group on the coating (e.g. a hydroxy, amino or epoxy group) and an acid anhydride group or proton donating group on the surface.